Initial interaction between the target and laser pulse for the excitation of plasma x-ray lasers and EUV sources is investigated using a hydrodynamics model, which takes liquid gas phase transition and particle emission from the ablation of the target material into account. Investigations are carried out for the irradiation of relatively weak pre-pulse laser pulse, which produces particles and decides further heating by the main laser pulse and EUV emission.15th International Conference on X-Ray Lasers